Building with LLMs is powerful,  but unpredictable. Prompts changes, agents fail silently, and quality is hard to measure. LangWatch is building the next generation of dev tools for guaranteeing agents behave as expected. Our framework Scenario test agents end-to-end and ensure they deliver what is expected through agent simulations.

Our platform combines LLMOps, evals, prompt management and agent testing into one cohesive workflow, making AI systems as measurable and trustworthy as any other software, unblocking the world to actually ship agents reliably.

Backed by Passion Capital and Antler, we’re based in Amsterdam and trusted by teams building the next generation of AI products.

Why LangWatch?

• Well backed startup by Passion Capital & Antler.
• Foundational OpenSource
• Stay at the forefront of AI technology.
• Compensation & equity: Competitive salary plus stock options
• Work closely with two ambitious co-founders and an amazing entrepreneurial technical driven team to solve this major painpoint for teams building AI agents.
• Small, focused, in-person team in the heart of Amsterdam. (The Hackerbuilding)

You're a fit if you:

• Ex-CTO: Want to ship code and own the product again, moving past management.
• Thrive in fast-paced sprints.
• Hate over-engineering and unnecessary meetings.
• Have a low-ego, high-ownership mindset; you do what needs to be done.

What you'll be doing

This is a product-driven, high-ownership engineering role.

• Build, deploy, and own new features end-to-end across FE (React), BE (TypeScript/Python), SDKs, and documentation.
• Architect a scalable, future-proof tech foundation that prioritizes speed.
• Propose, plan, and execute major platform features (you are the PM and developer).
• Handle technical user support; this is a key product feedback loop.
• Engage directly with users to understand needs.

What you'll bring

• Deep expertise building and deploying LLM/AI applications or agentic systems.
• Proven ability to autonomously PM and execute projects rapidly.
• Experience building highly reliable, scaling SaaS infrastructure.
• Solid full-stack development experience in our core stack: TypeScript, React, and Python.
• A strong builder mentality, prioritizing action and big-picture strategy.
• Impressive technical achievements.

Bonus points

• Experience in SDK design or strong Developer Experience (DX) background.
• Former founder or early-stage employee.
• CS or quantitative degree preferred.